The present invention relates to a sheet paper attracting system for use in a sheet paper feeding system of a copying machine, a facsimile system, a printing machine, etc.
Various types of sheet paper feeding systems have been developed for supplying a paper sheet from a storing section where a plurality of sheets are stacked. One type of the sheet paper feeding system employs a sheet feed roller for catching a paper sheet through the use of the friction caused by the rotating sheet feed roller. This type of sheet paper feeding system may damage the surface of the paper sheet. Furthermore, an accurate feeding operation is not ensured when the sheet paper has a low friction factor, or when the surface construction of the sheet feed roller is deteriorated due to long time usage.
Another type of the sheet paper feeding system employs an air pump for attracting a paper sheet. More specifically, a sheet paper attracting unit is connected to a suction air casing which includes a vacuum chamber therein. The sheet paper attracting unit faces the uppermost paper sheet stored in the storing section. In the conventional system, the sheet paper attracting unit is tightly fixed to the suction air casing and, therefore, an accurate attracting operation is not ensured when the paper sheet has an uneven surface, or when the relationship between the locations of the sheet paper attracting unit and the sheet paper storing section is not exactly adjusted.
Accordingly, an object of the present invention is to provide a sheet paper attracting system which ensures an accurate paper sheet feeding operation.
Another object of the present invention is to provide a mechanism which allows an adjusting movement of a sheet paper attracting unit with respect to a suction air casing.
Still another object of the present invention is to provide a sheet paper attracting system which prevents the piled feeding of paper sheets even when the thickness of the paper sheet varies.
A further object of the present invention is to provide a control system which ensures a smooth feeding in a paper sheet attracting system.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, the sheet paper attracting unit is connected to the suction air casing via a flexible duct so that the sheet paper attracting unit is movable with respect to the suction air casing.
In a preferred form, an attracting suction force control circuit is provided for varying the suction force in accordance with the thickness of a paper sheet. Furthermore, the sheet paper attracting unit is constructed to rotate by a predetermined angle while the center of a paper sheet is depressed by a depression roller in order to prevent the piled feeding of paper sheets. The leading edge of a paper sheet attracted by the sheet paper attracting unit is caught by a sheet feeding member. When the sheet feeding member is enabled to feed the paper sheet, the suction operation is terminated and the depression roller is pulled upward in order not to disturb the sheet feeding operation.